polar_encoder.h

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/* -*- c++ -*- */
/*
 * Copyright 2015 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 */
 
 
#ifndef INCLUDED_FEC_POLAR_ENCODER_H
#define INCLUDED_FEC_POLAR_ENCODER_H
 
#include <gnuradio/fec/api.h>
#include <gnuradio/fec/generic_encoder.h>
#include <gnuradio/fec/polar_common.h>
 
namespace gr {
namespace fec {
namespace code {
 
/*!
 * \brief POLAR encoder
 * for basic details see 'polar_common' class.
 * \ingroup error_coding_blk
 *
 * \details
 * expects values with MSB first. It needs a full information word and encodes it in one
 * pass. Output is a codeword of block_size.
 */
class FEC_API polar_encoder : public generic_encoder, public polar_common
{
public:
    /*!
     * Factory for a polar code encoder object.
     *
     * \param block_size defines the codeword size. It MUST be a
     *        power of 2.
     * \param num_info_bits represents the number of information
     *        bits in a block. Also called frame_size.
     * \param frozen_bit_positions is an integer vector which
     *        defines the position of all frozen bits in a block.
     *        Its size MUST be equal to block_size - num_info_bits.
     *        Also it must be sorted and every position must only
     *        occur once.
     * \param frozen_bit_values holds an unpacked byte for every
     *        frozen bit position. It defines if a frozen bit is
     *        fixed to '0' or '1'. Defaults to all ZERO.
     * \param is_packed choose 1 active bit/byte or 8 active
     *        bit/byte. if false, VOLK polar encoder is used.
     */
    static generic_encoder::sptr make(int block_size,
                                      int num_info_bits,
                                      std::vector<int> frozen_bit_positions,
                                      std::vector<uint8_t> frozen_bit_values,
                                      bool is_packed = false);
    ~polar_encoder() override;
 
    // FECAPI
    void generic_work(void* in_buffer, void* out_buffer) override;
    double rate() override { return (1.0 * get_input_size() / get_output_size()); };
    int get_input_size() override { return num_info_bits() / (d_is_packed ? 8 : 1); };
    int get_output_size() override { return block_size() / (d_is_packed ? 8 : 1); };
    bool set_frame_size(unsigned int frame_size) override { return false; };
    const char* get_input_conversion() override { return d_is_packed ? "pack" : "none"; };
    const char* get_output_conversion() override
    {
        return d_is_packed ? "packed_bits" : "none";
    };
 
private:
    polar_encoder(int block_size,
                  int num_info_bits,
                  std::vector<int>& frozen_bit_positions,
                  std::vector<uint8_t>& frozen_bit_values,
                  bool is_packed);
    bool d_is_packed;
 
    // Helper function to allow `d_frozen_bit_prototype` to be const.
    volk::vector<unsigned char> make_prototype() const;
 
    // methods insert input bits and frozen bits into packed array for encoding
    const volk::vector<unsigned char>
        d_frozen_bit_prototype; // packed frozen bits are written onto it and
                                // later copies are used.
    void insert_packed_frozen_bits_and_reverse(unsigned char* target,
                                               const unsigned char* input) const;
    void insert_unpacked_bit_into_packed_array_at_position(unsigned char* target,
                                                           const unsigned char bit,
                                                           const int pos) const;
    void insert_packet_bit_into_packed_array_at_position(unsigned char* target,
                                                         const unsigned char bit,
                                                         const int target_pos,
                                                         const int bit_pos) const;
 
    // packed encoding methods
    void encode_vector_packed(unsigned char* target) const;
    void encode_vector_packed_subbyte(unsigned char* target) const;
    void encode_packed_byte(unsigned char* target) const;
    void encode_vector_packed_interbyte(unsigned char* target) const;
};
 
} // namespace code
} // namespace fec
} // namespace gr
 
#endif /* INCLUDED_FEC_POLAR_ENCODER_H */